In wireless communication, the success of data transmission is typically related to the power and/or energy used for transmission. For example, a data message transmitted using a high power typically has a better chance of reaching the intended receiver in a detectable and readable condition than has the same data message transmitted using a lower power.
On the other hand, in multiuser systems it is typically beneficial if transmissions are not made using a higher power than necessary.
Thus, there is typically an interval or a precise value relating to the transmission power that should preferably be used by a particular transmitting unit. This interval or value may typically vary with time. The variations may, for example, be due to movement of the particular transmitting unit and other units of the communication system, but may also be due to changing of other environmental conditions, such as temperature, air pressure, movement of objects in the environment, varying traffic load in the system, varying shielding of the transmitting unit, etc. Many communication standards have implemented power control protocols to provide the transmitting unit with information relating to the currently preferred transmission power.
Wireless transmitting units are typically battery powered. Thus, energy consumption is an important factor for the operation of such units. This may be particularly important when considering machine type communications (MTC), i.e. communication between units where no human interaction is directly involved in the communication.
Machine Type Communication, sometimes also referred to as Machine-to-Machine (M2M) communication, is expected to be utilized for a huge variety of applications. For many of these applications, one or more of the units involved should preferably be able to function without any service (e.g. battery change or battery charging requiring human interaction) for long periods of time (e.g. months, years or even decades). Furthermore, it may be desirable to run such units using small and/or standard of-the-shelf batteries (such as coin cell batteries) and/or using e.g. solar energy from a small size solar panel.
US 2006/0270385 discloses a method for controlling data transmission based on power cost. A power cost per unit data associated with successfully sending data is determined. The determined power cost per unit data is compared to a threshold, and transmission of data is delayed based on a determination that the power cost per unit data exceeds the threshold. The data transmission is delayed until the power cost per unit data is below a threshold. The power consumption rate used for determining the power cost per unit data may be obtained by measuring a power consumption rate associated with the transmission of data, and/or by using a closed loop power control scheme where a received signal strength indicator of a data transmission is measured at a receiver of the data transmission and provided to the transmitter to be used to set a signal strength for the transmitted signal.
US 2012/0129564 A1 discloses a communication device adapted to determine a measured network condition associated with transmitting an initial communication and to determine a power consumption of the initial communication based on a measured network condition value. The power consumption of the initial communication is compared with a predetermined power consumption value and communication is terminated if the power consumption of the initial communication exceeds the predetermined power consumption value.
However, when no data has been transmitted recently, the power consumption rate cannot be reliably determined according to these methods. Furthermore, it would be desirable to even further reduce the energy consumption and to provide for an implementation that is functional also where no closed loop power control protocol is applicable.
Therefore, there is a need for methods and arrangements for improved transmission control and in particular for applications having tough power/energy constraints.